Fully transparent design of a hybrid optical packet/circuit metropolitan area network

We present a new method to design a regional network based on optical hybrid packet and circuit switching. Our approach aims at providing packet-level grooming only where it is profitable. The method relies on splitting the original traffic matrix in two parts, which will be transported either through optical packets or through circuits, according to a maximum wavelength capacity threshold. The network dimensioning can be then performed for circuit and packet traffic matrices separately. As the circuit WDM network design problem is well documented, we put the emphasis on the optical packet network dimensioning. This later is performed in the context of Packet OADM (POADM) technology, involving fast tuneable emitters and receivers dedicated to specific wavelengths. First, candidate sets of rings are identified. Then, the resources needed for each ring of a given set are evaluated by taking into account both. receiver and wavelength costs. The “wavelength cost” depends on the considered ring, as it is proportional to its circumference. A linear programing formulation, previously established for unidirectional rings, is adapted to bi-directional ones with shortest distance routing and 1+1 protection. The proposed method is applied to a 7 nodes network by considering different scenarios in terms of content-delivery node positions, wavelength capacity threshold or network geographical extension. Even if most of the traffic is carried by circuits, POADM technology is widely used as a grooming technique across the network. The benefits of using POADM technology are achieved without necessitating O/E/O conversions at packet ring interconnections and alleviating inter-ring synchronization issues, resulting in a fully transparent network.